This invention relates to a multifocal ophthalmic lens and in particular to a lens adapted for implantation in an eye, such as an intraocular lens (IOL), or to be disposed on or in the cornea, such as a contact lens, corneal onlay or corneal inlay. The corneal inlay may also be regarded as an implant.
A specific embodiment shown in my U.S. Pat. No. 4,898,461 (which patent is incorporated by reference herein) discloses a multifocal ophthalmic lens which includes a central zone circumscribed by multiple concentric, annular zones. The central zone may have a vision correction power for intermediate correction and from there the vision correction power varies progressively in a radial outward direction to a far vision correction power, and then to a near vision correction power. In the specific embodiment of this patent, the progressive vision correction power is varied between far and near through the several zones.
A multifocal ophthalmic lens of this type provides multiple images on the retina. One or more of these images is in focus and one or more of these images is out of focus. The human brain selects the in-focus image to enable a multifocal ophthalmic lens of this type to function well at near, intermediate and far viewing distances.